The most widely used cell culture method is currently to culture cells in a two-dimensional well plate or culture dish. However, according to recent papers, two-dimensional (monolayer) cell culture causes lower cell functions and significantly changed morphology compared with three-dimensional cell culture (Proc. Natl. Acad. Sci. USA, 100: 1943-1948, 2003; Cell, 111: 923-925, 2002; Cancer Cell 2: 205-216, 2002). In order to overcome these disadvantages, cell culture methods using three-dimensional structured supports have been recently developed, and electrospinning, foam molding, method ionic concentration, and making inversion structures using spherical self-assemblies are widely employed as methods for making such structures. In recent years, a new paradigm of cell culture method that creates an environment similar to the in vivo environment has been attempted through the development of the field of a bio-MEMS, called DNA chips, protein chips, and integrated chips, which is a microelectromechanical system used in the biomedical field (Proc. Natl. Acad. Sci. USA, 96: 5545-5548, 1999; Anal. Chem., 74: 1560-1564, 2002; Biotechnol. Prog., 20: 338-345, 2004; Biomed. Microdevices, 4: 161-166, 2002). Similarly, Korean Patent No. 10-0733914 discloses a three-dimensional microcellular culture system characterized in that cells exist in a three-dimensional gel, but the system has disadvantages in that it is difficult to separate the cells existing in the gel in the cell subculture or analysis using cells after cell culture, and especially, stem cells or primary cells, which are difficult to adhere and proliferate, are damaged during cell separation.
Stem cells refer to cells that can proliferate indefinitely in an undifferentiated state as well as differentiating to have a specialized function and shape under specific environments and conditions. Human embryonic stem cells enable continuous self-renewal under appropriate in vitro culture conditions and have pluripotency to differentiate into all of the cell types that make up the body. Therefore, the application range of study results on human embryonic stem cells is expanding to a wide variety of aspects, such as: the understanding of basic knowledge of development, differentiation, and growth of the human body; the development of cell therapy products for the fundamental treatment of damages or various diseases of the human body; the screening of the efficacy for various novel drug candidates; and the establishment of causes of diseases, the development of therapeutic strategies.
Meanwhile, primary cells refer to cells that are directly primarily cultured from animal tissues or organs, and the primary cells are normal cells obtained from living cells. The primary cells, unlike tumor cells, have a limit in the artificial in vitro subculture. The primary cells are used in the production of biological drugs or the like and have also been developed as cell therapeutics due to an advantage of being similar to an actual biological reaction.